ALTERNATIVES FOR RAINWATER STORAGE: PACHUCA DE SOTO (CENTRAL MEXICO) – A PRELIMINARY CASE STUDY

The Pachuca de Soto City and the suburban area, situated in the state of Hidalgo (Central Mexico) lacks of an efficient system for collecting rainwater, in despite that the annual average precipitation reaches about 800 mm. In this abstract we propose in a preliminary way a series of alternatives for collecting rainwater in the study area, considering both natural and engineering aspects. The study area is located in the Trans Mexican Volcanic Belt and is surrounded by the Sierra de Tezontlalpan at west, Sierra de Pachuca at northeast, and the Pachuca-Tizayuca valley at south. It is characterized by a temperate and relative humid climate [BS₁k’w(w)(i’), with an annual average temperature of 15 ^oC] and an annual average precipitation of 800 mm. The rainy season occurs from May to October, being June, July and August the rainiest. Considering the factors mentioned above, the methodology we used to know the collecting water volumes in different zones of the city were the following: 1) We determined the main slopes of superficial runoff, locating former runoffs, artificial runoffs, sewage collectors, channels and aqueducts; 2) we measured different hydrological parameters such as runoff surfaces, infiltration capacity, runoff velocities, as well as average precipitation, evaporation and temperature, in order to calculate flooding areas, as well as the potentially collected volume of water. The preliminary results showed that for those zones located in the Western, Northern and Eastern zones of the study area, situated in the foothills of the Sierras de Pachuca and Tezontepec, the most viable alternative is the construction of a well-designed pipe system that collects and transports rainwater to special storage areas. By the other hand, for the Southern zone of the study area, placed in the valley area of Pachuca City, the alternative we proposed is to use permeable pavements that facilitate the infiltration of the rainwater and allow the recharge of the regional aquifer. According to these alternatives, the current water deficit that affects the City of Pachuca could be reduced considerably as long as these alternatives are applied.